﻿// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
// Copyright (c) 2011, Dr. Masroor Ehsan
// All rights reserved.
// 
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above copyright
//       notice, this list of conditions and the following disclaimer in the
//       documentation and/or other materials provided with the distribution.
//     * Neither the name of the author nor the
//       names of its contributors may be used to endorse or promote products
//       derived from this software without specific prior written permission.
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
// DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// 
// $Author:$
// $Id:$
// $Rev:$
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

using System.Collections.Generic;
using System.Linq;
using NodaTime;

namespace nodatest
{
    public static class DateTimeUtils
    {
        private static readonly List<TimeZoneHandler> _timezonesList = GetTimeZonesList();

        public static IEnumerable<TimeZoneHandler> AllTimeZones
        {
            get { return _timezonesList; }
        }

        private static List<TimeZoneHandler> GetTimeZonesList()
        {
            var list = new List<TimeZoneHandler>();
            foreach (var id in DateTimeZone.Ids)
            {
                list.Add(new TimeZoneHandler(DateTimeZone.ForId(id)));
            }
            return list;
        }

        public static List<TimeZoneHandler> TimeZonesForRegion(string region)
        {
            return _timezonesList.Where(t => string.Compare(t.RegionClass, region) == 0).ToList();
        }

        internal static string RegionFromTimeZoneId(string id)
        {
            if (id.IndexOf('/') != -1)
            {
                return PrettyTimeZoneName(id.Substring(0, id.LastIndexOf('/')));
            }
            return PrettyTimeZoneName(id);
        }

        internal static string PrettyTimeZoneName(string id)
        {
            if (id.IndexOf('_') != -1) id = id.Replace('_', ' ');
            return id;
        }

        public static List<string> TimeZoneRegions()
        {
            return _timezonesList.Select(t => t.RegionClass).Distinct().ToList();
        }

        public static TimeZoneHandler SystemTimeZone()
        {
            return new TimeZoneHandler(DateTimeZone.SystemDefault);
        }

        public static TimeZoneHandler UniversalTimeZone()
        {
            return new TimeZoneHandler(DateTimeZone.Utc);
        }

        public static TimeZoneHandler FindId(string id)
        {
            return (from tz in _timezonesList
                    where string.Compare(tz.Id, id) == 0
                    select tz).FirstOrDefault();
        }
    }
}